Max Mosley, the president of Formula One's world governing body FIA, hit back at the team heads Frank Williams and Ron Dennis yesterday, accusing them of acting irresponsibly and destabilising the sport with the new season days away.

Mosley has sent a strongly-worded four-page letter answering their criticisms over recent changes to the sport. Williams and his McLaren counterpart, Dennis, last week accused Mosley of acting in a dictatorial manner and of dumbing down Formula One after introducing moves to lower costs and make the sport more attractive.

The pair wrote to Mosley announcing that they would take the FIA to arbitration, although as that process could take a year they confirmed they would abide by the regulations in the 2003 season, which begins on Friday week.

"Your response is unfocused," Mosley replied, insisting that his aim was to attract new entrants and preserve the 10 teams already in Formula One. "It is impossible to have a dialogue if the response to a carefully considered set of proposals is a collection of vague claims and confused criticisms, with no discernible attempt to address the arguments.

"You both knew perfectly well that, at least until 15 January, there was great unease among sponsors, television networks and race promoters about Formula One. You must also have known that to announce your intention to go to arbitration would add to the unease and revive all the worries of the winter break.

"Yet, having instructed solicitors to write to us on 20 February saying that arbitration proceedings would commence unless we agreed to compromise by 26 February, you went to the world's media on 20 February without waiting for a response, indeed before we even had the letter. How irresponsible.

"You waited five weeks after the 15 January meeting without reacting or seeking a meeting. Could you not have waited another six days for our response to your solicitors' letter before once again destabilising the FIA Formula One World Championship?"

Mosley dismissed the charge that he is dumbing down Formula One by moving to abolish driver aids such as traction, launch control and two-way computer telemetry, through which teams can alter car settings during a race.

"If you truly believe the public want to see computer-controlled cars guided from the pits by anonymous engineers, please think again," Mosley added. "If you don't believe me, hire two halls in any city anywhere in the world and put, for example, Michael Schumacher, Kimi Raikkonen and Juan Pablo Montoya in one, with both of you plus your electronics experts and your technical chiefs in the other.

"Invite the public to both halls and see what happens. The public are interested in drivers and sport, not electronics."

Mosley also ridiculed the team chiefs' claim that the move to cut to two and a half hours the amount of time mechanics could work on the car between qualifying and races would make the sport unsafe.

"You are saying that after less than 150km of free practice on Saturday morning your cars cannot safely race for 300km without an 18-hour overhaul," he said. "This is obvious nonsense. We have all seen cars completely rebuilt in less than two hours after a major accident. Yours is a really threadbare argument."